Their two centurians, Stuart Law and Nasser Hussain, put on 317 for the third wicket in 77 overs and Ronnie Irani and Paul Grayson tucked in after that.
Essex batted on until 35 minutes before the end of the second day hoping that the pitch will take spin, as usually happens here, and that they will win by an innings. They have made a good start, and they are well prepared as they are playing two off-spinners, Peter Such and Jonathan Powell, who is playing his first Championship.
On the first day, Law had outscored Hussain by a margin of two-to-one, but, yesterday Hussain began with three successive fours in the third over of the morning against David Millns and was altogether more authoritative. Law bided his time while Hussain took most of the strike early on but then square-cut Millns and pulled Alan Mullally with most decisive strokes.
Law's assurance is bewildering and this was his 17th hundred in all cricket for Essex since he joined them last year, which shows how extraordinarily consistent he has been.
Curiously, Hussain, who has made two hundreds, one a double, in the Test series, reached three figures for his county for the first time this year.
The only dampening factor on one of the country's most beautiful festival grounds is the fear that the new format of county cricket, whatever it may be, will produce fewer home games and therefore a possibility that centres like Colchester will lose their annual five days county cricket.
Colchester is a big catchment area for support in Essex and the local council, supported by businesses in the area, are happily doing their best to ensure that the occasion is preserved.
Once Leicestershire had lost the toss, their fate was almost pre-ordained. They do not have quite the buzz of potential champions, which was theirs at the end of last season, but they are in the upper reaches of the table and there is still plenty of cricket to be played.
Law's innings was the first to come to an end when he went down the pitch as if to drive Matthew Brimson on to Mersea Island and was stumped. He faced 233 balls and hit 23 fours and three sixes.
Hussain was similarly adventurous and gave a catch to James Whitaker at short third man after facing 289 balls and hitting 15 fours and one six.
This brought together Irani and Grayson, who, with comparable power if not elegance, put on 143 in 33 overs. Hardly surprisingly, the Leicestershire bowling wilted somewhat and it became simply a question of waiting for the declaration.